X = int(input()) Y = int(input()) Z = int(input()) N = int(input()) ans = [[i, j, k] for i in range(X + 1) for j in range(Y

Question

can someone explain this code?
https://code.sololearn.com/cpW9tGC1lOQ0/?ref=app

Answer 1

If you take the expression out of the list comprehension and put it this way it might be more clear for you to understand what it is suppose to do

for i in range(X+1):
for j in range(Y+1):
for k in range(Z+1):
if(i+j+k)!=N:
print([i,j,k])

So suppose all the inputs are 1

Now when the loop starts i=0,j=0,k=0,since 0+0+0 is not equal to 1 it prints [0,0,0]
And as you know inner loop is executed first so in the next iteration we have i=0,j=0,k=1,since 0+0+1 is equal to 1 ,it doesn't prints this series ,

In next iteration we will have i=0,j=1,k=0 ,then for i=0,j=1,k=1 and so on

Answer 2

Jaya Pratha , the code creates a number of combinations (permutations) in a list using nested loops. Similar things can also be done by using python module itertools.permutation.